JDT LS Filesystem should respect resource filtering

- Resource model filtering is set up after projects are imported, but
  some import operations (eg. Maven projects) could benefit from this

org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/preferences/PreferenceManager.java

@@ -227,6 +227,10 @@ public void update(Preferences preferences) {
 		Hashtable<String, String> options = JavaCore.getOptions();
 		preferences.updateTabSizeInsertSpaces(options);
 		JavaCore.setOptions(options);
+		List<String> resourceFilters = preferences.getResourceFilters();
+		IEclipsePreferences eclipsePreferences = InstanceScope.INSTANCE.getNode(IConstants.PLUGIN_ID);
+		// add the resourceFilters preference; the org.eclipse.jdt.ls.filesystem plugin uses it
+		eclipsePreferences.put(Preferences.JAVA_RESOURCE_FILTERS, String.join("::", resourceFilters));
 		// TODO serialize preferences
 	}
 

org.eclipse.jdt.ls.filesystem/src/org/eclipse/jdt/ls/core/internal/filesystem/JDTLSFilesystemActivator.java

@@ -1,5 +1,14 @@
 package org.eclipse.jdt.ls.core.internal.filesystem;
 
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+import java.util.regex.Pattern;
+
+import org.eclipse.core.runtime.preferences.IEclipsePreferences;
+import org.eclipse.core.runtime.preferences.IEclipsePreferences.IPreferenceChangeListener;
+import org.eclipse.core.runtime.preferences.IEclipsePreferences.PreferenceChangeEvent;
+import org.eclipse.core.runtime.preferences.InstanceScope;
 import org.osgi.framework.BundleActivator;
 import org.osgi.framework.BundleContext;
 
@@ -15,17 +24,60 @@
 public class JDTLSFilesystemActivator implements BundleActivator {
 
 	private static BundleContext context;
+	private static final String JAVA_LS_PLUGIN_ID = "org.eclipse.jdt.ls.core";
+	private static final String JAVA_RESOURCE_FILTERS = "java.project.resourceFilters";
+	private static final String JAVA_RESOURCE_FILTERS_DEFAULT = "node_modules::\\.git";
+	private List<Pattern> resourcePatterns; 
+	private String resourceFilters;
+	private static JDTLSFilesystemActivator instance;
 
 	static BundleContext getContext() {
 		return context;
 	}
 
 	public void start(BundleContext bundleContext) throws Exception {
 		JDTLSFilesystemActivator.context = bundleContext;
+		JDTLSFilesystemActivator.instance = this;
+		configureResourceFilters();
+	}
+
+	private void configureResourceFilters() {
+		IEclipsePreferences eclipsePreferences = InstanceScope.INSTANCE.getNode(JAVA_LS_PLUGIN_ID);
+		if (eclipsePreferences != null) {
+			resourceFilters = eclipsePreferences.get(JAVA_RESOURCE_FILTERS, JAVA_RESOURCE_FILTERS_DEFAULT);
+			eclipsePreferences.addPreferenceChangeListener(new IPreferenceChangeListener() {
+
+				@Override
+				public void preferenceChange(PreferenceChangeEvent event) {
+					if (event.getNewValue() instanceof String newValue && Objects.equals(JAVA_RESOURCE_FILTERS, event.getKey()) && !Objects.equals(resourceFilters, event.getNewValue())) {
+						resourceFilters = newValue;
+						setResourcePatterns();
+					}
+				}
+			});
+		} else {
+			resourceFilters = JAVA_RESOURCE_FILTERS_DEFAULT;
+		}
+		setResourcePatterns();
+	}
+
+	protected void setResourcePatterns() {
+		resourcePatterns = new ArrayList<>();
+		for (String element : resourceFilters.split("::")) {
+			Pattern pattern = Pattern.compile(element);
+			resourcePatterns.add(pattern);
+		}
 	}
 
 	public void stop(BundleContext bundleContext) throws Exception {
 		JDTLSFilesystemActivator.context = null;
 	}
 
+	public static List<Pattern> getResourcePatterns() {
+		if (instance != null) {
+			return instance.resourcePatterns;
+		}
+		return null;
+	}
+
 }

org.eclipse.jdt.ls.filesystem/src/org/eclipse/jdt/ls/core/internal/filesystem/JLSFile.java

@@ -20,6 +20,7 @@
 
 import org.eclipse.core.filesystem.IFileStore;
 import org.eclipse.core.internal.filesystem.local.LocalFile;
+import org.eclipse.core.internal.preferences.EclipsePreferences;
 import org.eclipse.core.runtime.IPath;
 import org.eclipse.core.runtime.IProgressMonitor;
 import org.eclipse.core.runtime.Path;
@@ -50,6 +51,9 @@ public String[] childNames(int options, IProgressMonitor monitor) {
         }
 
         IPath filePath = new Path(this.filePath);
+        if (JLSFsUtils.isExcluded(filePath)) {
+            return childNames;
+        }
         String projectName = JLSFsUtils.getProjectNameIfLocationIsProjectRoot(filePath);
         if (projectName == null) {
             return childNames;
@@ -69,7 +73,7 @@ public String[] childNames(int options, IProgressMonitor monitor) {
     @Override
     public IFileStore getChild(String name) {
         IPath path = new Path(this.filePath).append(name);
-        if (JLSFsUtils.shouldStoreInMetadataArea(path)) {
+        if (JLSFsUtils.shouldStoreInMetadataArea(path) && !JLSFsUtils.isExcluded(path)) {
             IPath containerPath = JLSFsUtils.getContainerPath(path);
             String projectName = JLSFsUtils.getProjectNameIfLocationIsProjectRoot(containerPath);
             if (projectName == null) {
@@ -87,7 +91,7 @@ public IFileStore getChild(String name) {
     @Override
     public IFileStore getFileStore(IPath path) {
         IPath fullPath = new Path(this.filePath).append(path);
-        if (JLSFsUtils.shouldStoreInMetadataArea(fullPath)) {
+        if (JLSFsUtils.shouldStoreInMetadataArea(fullPath) && !JLSFsUtils.isExcluded(fullPath)) {
             IPath containerPath = JLSFsUtils.getContainerPath(fullPath);
             String projectName = JLSFsUtils.getProjectNameIfLocationIsProjectRoot(containerPath);
             if (projectName == null) {

org.eclipse.jdt.ls.filesystem/src/org/eclipse/jdt/ls/core/internal/filesystem/JLSFsUtils.java

@@ -17,13 +17,17 @@
 import java.util.HashSet;
 import java.util.Objects;
 import java.util.Set;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 import org.eclipse.core.internal.preferences.EclipsePreferences;
 import org.eclipse.core.resources.IContainer;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.resources.IProjectDescription;
 import org.eclipse.core.resources.ResourcesPlugin;
 import org.eclipse.core.runtime.IPath;
+import org.eclipse.core.runtime.preferences.IEclipsePreferences;
+import org.eclipse.core.runtime.preferences.InstanceScope;
 import org.eclipse.jdt.core.IJavaProject;
 
 /**
@@ -110,6 +114,27 @@ static boolean isProjectMetadataFile(IPath location) {
         return true;
     }
 
+    /**
+     * Check whether the given location is excluded
+     * @param location file location.
+     * @return whether the given location is excluded.
+     */
+    public static boolean isExcluded(IPath path) {
+        if (path != null && JDTLSFilesystemActivator.getResourcePatterns() != null) {
+            for (String segment: path.segments()) {
+                for (Pattern pattern: JDTLSFilesystemActivator.getResourcePatterns()) {
+                    Matcher m = pattern.matcher(segment);
+                    if (m.matches()) {
+                        return true;
+                    }
+                }
+            }
+            return false;
+        } else {
+            return true;
+        }
+    }
+
     /**
      * Get the container path of the given file path.
      * If the file path is a preferences file, the grand-parent container will be returned.

org.eclipse.jdt.ls.tests/src/org/eclipse/jdt/ls/core/internal/filesystem/JLSFsUtilsTest.java

@@ -16,6 +16,9 @@
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
+import org.eclipse.core.runtime.IPath;
+import org.eclipse.core.runtime.Path;
+import org.junit.After;
 import org.junit.Test;
 
 public class JLSFsUtilsTest {
@@ -35,4 +38,15 @@ public void testNotGeneratesMetadataFilesAtProjectRoot() {
 	public void testGeneratesMetadataFilesAtProjectRootWhenNotSet() {
 		assertTrue(JLSFsUtils.generatesMetadataFilesAtProjectRoot());
 	}
+
+	@Test
+	public void testExcluded() {
+		IPath path = new Path("/project/node_modules");
+		assertTrue(JLSFsUtils.isExcluded(path));
+	}
+
+	@After
+	public void cleanUp() throws Exception {
+		System.clearProperty(JLSFsUtils.GENERATES_METADATA_FILES_AT_PROJECT_ROOT);
+	}
 }

org.eclipse.jdt.ls.tests/src/org/eclipse/jdt/ls/core/internal/managers/AbstractProjectsManagerBasedTest.java

@@ -97,6 +97,8 @@ public abstract class AbstractProjectsManagerBasedTest {
 
 	private static final java.lang.String REFERENCE_PREFIX = "reference:";
 
+	private static final String GENERATES_METADATA_FILES_AT_PROJECT_ROOT = "java.import.generatesMetadataFilesAtProjectRoot";
+
 	protected IProgressMonitor monitor;
 	protected StandardProjectsManager projectsManager;
 	@Mock
@@ -302,6 +304,7 @@ public void cleanUp() throws Exception {
 		}
 		ResourcesPlugin.getWorkspace().save(true/*full save*/, null/*no progress*/);
 		CoreASTProvider.getInstance().disposeAST();
+		System.clearProperty(GENERATES_METADATA_FILES_AT_PROJECT_ROOT);
 	}
 
 	protected void assertIsJavaProject(IProject project) {